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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org,
	Abhishek Shah <abhishek.shah@columbia.edu>,
	Takashi Iwai <tiwai@suse.de>
Subject: [PATCH 4.9 22/42] ALSA: seq: Fix data-race at module auto-loading
Date: Tue, 13 Sep 2022 16:07:53 +0200	[thread overview]
Message-ID: <20220913140343.398413497@linuxfoundation.org> (raw)
In-Reply-To: <20220913140342.228397194@linuxfoundation.org>

From: Takashi Iwai <tiwai@suse.de>

commit 3e7e04b747adea36f349715d9f0998eeebf15d72 upstream.

It's been reported that there is a possible data-race accessing to the
global card_requested[] array at ALSA sequencer core, which is used
for determining whether to call request_module() for the card or not.
This data race itself is almost harmless, as it might end up with one
extra request_module() call for the already loaded module at most.
But it's still better to fix.

This patch addresses the possible data race of card_requested[] and
client_requested[] arrays by replacing them with bitmask.
It's an atomic operation and can work without locks.

Reported-by: Abhishek Shah <abhishek.shah@columbia.edu>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/CAEHB24_ay6YzARpA1zgCsE7=H9CSJJzux618E=Ka4h0YdKn=qA@mail.gmail.com
Link: https://lore.kernel.org/r/20220823072717.1706-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 sound/core/seq/seq_clientmgr.c |   12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

--- a/sound/core/seq/seq_clientmgr.c
+++ b/sound/core/seq/seq_clientmgr.c
@@ -136,13 +136,13 @@ struct snd_seq_client *snd_seq_client_us
 	spin_unlock_irqrestore(&clients_lock, flags);
 #ifdef CONFIG_MODULES
 	if (!in_interrupt()) {
-		static char client_requested[SNDRV_SEQ_GLOBAL_CLIENTS];
-		static char card_requested[SNDRV_CARDS];
+		static DECLARE_BITMAP(client_requested, SNDRV_SEQ_GLOBAL_CLIENTS);
+		static DECLARE_BITMAP(card_requested, SNDRV_CARDS);
+
 		if (clientid < SNDRV_SEQ_GLOBAL_CLIENTS) {
 			int idx;
 			
-			if (!client_requested[clientid]) {
-				client_requested[clientid] = 1;
+			if (!test_and_set_bit(clientid, client_requested)) {
 				for (idx = 0; idx < 15; idx++) {
 					if (seq_client_load[idx] < 0)
 						break;
@@ -157,10 +157,8 @@ struct snd_seq_client *snd_seq_client_us
 			int card = (clientid - SNDRV_SEQ_GLOBAL_CLIENTS) /
 				SNDRV_SEQ_CLIENTS_PER_CARD;
 			if (card < snd_ecards_limit) {
-				if (! card_requested[card]) {
-					card_requested[card] = 1;
+				if (!test_and_set_bit(card, card_requested))
 					snd_request_card(card);
-				}
 				snd_seq_device_load_drivers();
 			}
 		}



  parent reply	other threads:[~2022-09-13 15:31 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-13 14:07 [PATCH 4.9 00/42] 4.9.328-rc1 review Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 01/42] fbdev: fb_pm2fb: Avoid potential divide by zero error Greg Kroah-Hartman
2022-11-23  6:34   ` Ulrich Hecht
2022-11-30 16:41     ` Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 02/42] platform/x86: pmc_atom: Fix SLP_TYPx bitfield mask Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 03/42] wifi: cfg80211: debugfs: fix return type in ht40allow_map_read() Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 04/42] serial: fsl_lpuart: RS485 RTS polariy is inverse Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 05/42] staging: rtl8712: fix use after free bugs Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 06/42] vt: Clear selection before changing the font Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 07/42] USB: serial: ftdi_sio: add Omron CS1W-CIF31 device id Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 08/42] hwmon: (gpio-fan) Fix array out of bounds access Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 09/42] xhci: Add grace period after xHC start to prevent premature runtime suspend Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 10/42] USB: serial: cp210x: add Decagon UCA device id Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 11/42] USB: serial: option: add support for OPPO R11 diag port Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 12/42] USB: serial: option: add support for Cinterion MV32-WA/WB RmNet mode Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 13/42] USB: cdc-acm: Add Icom PMR F3400 support (0c26:0020) Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 14/42] usb-storage: Add ignore-residue quirk for NXP PN7462AU Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 15/42] s390/hugetlb: fix prepare_hugepage_range() check for 2 GB hugepages Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 16/42] s390: fix nospec table alignments Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 17/42] USB: core: Prevent nested device-reset calls Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 18/42] usb: gadget: mass_storage: Fix cdrom data transfers on MAC-OS Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 19/42] wifi: mac80211: Dont finalize CSA in IBSS mode if state is disconnected Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 20/42] net: mac802154: Fix a condition in the receive path Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 21/42] ALSA: seq: oss: Fix data-race for max_midi_devs access Greg Kroah-Hartman
2022-09-13 14:07 ` Greg Kroah-Hartman [this message]
2022-09-13 14:07 ` [PATCH 4.9 23/42] fs: only do a memory barrier for the first set_buffer_uptodate() Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 24/42] Revert "mm: kmemleak: take a full lowmem check in kmemleak_*_phys()" Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 25/42] drm/radeon: add a force flush to delay work when radeon Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 26/42] parisc: ccio-dma: Handle kmalloc failure in ccio_init_resources() Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 27/42] parisc: Add runtime check to prevent PA2.0 kernels on PA1.x machines Greg Kroah-Hartman
2022-09-13 14:07 ` [PATCH 4.9 28/42] fbdev: chipsfb: Add missing pci_disable_device() in chipsfb_pci_init() Greg Kroah-Hartman
2022-09-13 14:08 ` [PATCH 4.9 29/42] ALSA: emu10k1: Fix out of bounds access in snd_emu10k1_pcm_channel_alloc() Greg Kroah-Hartman
2022-09-13 14:08 ` [PATCH 4.9 30/42] ALSA: aloop: Fix random zeros in capture data when using jiffies timer Greg Kroah-Hartman
2022-09-13 14:08 ` [PATCH 4.9 31/42] ALSA: usb-audio: Fix an out-of-bounds bug in __snd_usb_parse_audio_interface() Greg Kroah-Hartman
2022-09-13 14:08 ` [PATCH 4.9 32/42] scsi: mpt3sas: Fix use-after-free warning Greg Kroah-Hartman
2022-09-13 14:08 ` [PATCH 4.9 33/42] driver core: Dont probe devices after bus_type.match() probe deferral Greg Kroah-Hartman
2022-09-13 14:08 ` [PATCH 4.9 34/42] netfilter: br_netfilter: Drop dst references before setting Greg Kroah-Hartman
2022-09-13 14:08 ` [PATCH 4.9 35/42] netfilter: nf_conntrack_irc: Fix forged IP logic Greg Kroah-Hartman
2022-09-13 14:08 ` [PATCH 4.9 36/42] sch_sfb: Dont assume the skb is still around after enqueueing to child Greg Kroah-Hartman
2022-09-13 14:08 ` [PATCH 4.9 37/42] tipc: fix shift wrapping bug in map_get() Greg Kroah-Hartman
2022-09-13 14:08 ` [PATCH 4.9 38/42] tcp: fix early ETIMEDOUT after spurious non-SACK RTO Greg Kroah-Hartman
2022-09-13 14:08 ` [PATCH 4.9 39/42] sch_sfb: Also store skb len before calling child enqueue Greg Kroah-Hartman
2022-09-13 14:08 ` [PATCH 4.9 40/42] usb: dwc3: fix PHY disable sequence Greg Kroah-Hartman
2022-09-13 14:08 ` [PATCH 4.9 41/42] MIPS: loongson32: ls1c: Fix hang during startup Greg Kroah-Hartman
2022-09-13 14:08 ` [PATCH 4.9 42/42] SUNRPC: use _bh spinlocking on ->transport_lock Greg Kroah-Hartman
2022-09-14  9:50 ` [PATCH 4.9 00/42] 4.9.328-rc1 review Pavel Machek
2022-09-14 12:40 ` Naresh Kamboju
2022-09-14 15:26 ` Jon Hunter
2022-09-14 17:46 ` Florian Fainelli
2022-09-15  0:16 ` Guenter Roeck

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